The subject of this invention relates to the telephony industry. Specifically, this invention concerns implementation of incoming call screening on a customer premises equipment (CPE) for subscribers of a central voicemail service.
Call screening refers to a called party""s ability to aurally monitor a calling party without the calling party knowing that they are being listened to. Typically, called parties, or users, who desire such a function as call screening must use a telephone answering device (TAD), some other device such as a personal computer (PC), a live attendant, or a combination of these methods to provide the screening activity. The present invention stems from the need for a more cost effective and user efficient method of implementing the call screening function.
The use of dedicated call screening equipment such as a PC or a private branch exchange (PBX) requires significant investment in capital equipment and, in many cases, an attendant to qualify, or screen and transfer incoming calls. These methods, while successful, have limitations and/or disadvantages. For example, the hardware and software associated with dedicated equipment can be expensive. Additional costs such as salaries and maintenance fees can be high as well, adding to the overall cost of ownership. While a TAD offers the screening function at a reasonably low cost, it does so at the expense of user efficiency and flexibility. This is so because the user must be in close physical proximity to the TAD in order to listen to the incoming call, thus the TAD method suffers from a lack of user flexibility by limiting use of the call screening function to a specific location.
As a result of the breakup of ATandT in 1983 due to Federal antitrust action, the elimination of Bell Telephone as the single telephone service provider created several regional telephone service providers. Responding to increasing consumer competition these regional providers, referred to as the xe2x80x9cBaby Bells,xe2x80x9d began to offer services other than basic telephone connection. One of these services was a central office (CO) voicemail service. This centrally operated service allowed subscribing users to receive voicemail without the need for any special equipment at their premises. A plain old telephone service (POTS) CPE was all that was required, greatly reducing the cost of ownership for a voicemail service.
To use the service a user simply dialed into their account and operated the central system via a set of commands. The user could listen to messages, save, delete, forward or otherwise manipulate messages from their premises. However, use of the centrally served voicemail had a disadvantage. The user could no longer listen to the message, or screen calls as they were being left, an important capability available with a TAD or other call screening method.
As mentioned briefly above, there are at present a number of methods for accomplishing the call screening function in use, including CO based call screening service using centrally operated voicemail. For example, in one method, as long as the screening function is enabled by the user, the CO redirects all incoming calls to the user""s central voicemail service. When an incoming call is received the CO signals the user, who then must enter a dual tone multi-frequency (DTMF) code if he wishes to take the call. Thus a significant disadvantage of this method is the necessity for the user to enter a code each time he wishes to selectively screen a call. Obviously, errors in entry of the code or failure to react to the CO signal will cause the user to lose the opportunity to screen an incoming call.
In a second method the screening function, if selected by the user, is enabled via a radio link to the user""s cordless CPE. Disadvantageously, however, this method only works for incoming calls supporting caller identification (CID) and requires that the user pre-program a table containing all callers that are to be screened. Thus this method suffers from the dual disadvantages of increased complexity, i.e. the need to program numbers to be screened, and reduced user flexibility, i.e. the inability to screen calls not supported by CID.
Yet a third method presently in use involves the use of a TAD to accomplish a switching function in the user""s premises. With this method the TAD is placed between the user""s CPE and the public telephone line. An incoming call may be screened at any time by entry of a code by the user. A second public telephone line must also be attached to the TAD in order for the method to create a three-way call between the calling party, the user, and the CO. This method suffers from numerous disadvantages. First, two separate incoming public telephone lines are required, increasing the expense and complexity of the method. Second, each extension CPE within the user""s premises must be attached to a separate port on the TAD thereby increasing wiring cost, complexity, and the resultant decrease in reliability. Third, the screening function is not automatic. Each time the user wishes to screen an incoming call, a code must be entered which hampers efficient call screening activity.
As can be seen, all of the current methods suffer from one or more drawbacks. A further drawback common to all of the present methods is the inability to use the screening function with a cordless phone. A better method would be to provide a way for the user""s CPE to automatically establish a three-way call between the calling party, the user and the user""s central voicemail service without the need or any user intervention or special equipment. A further improvement would be for that method to allow use with cordless phones.
A cordless telephone includes a ring detector state machine module to facilitate the answering of a call received at the cordless telephone. A screening state machine module enables three-way connection and aural monitoring of the incoming call on the cordless telephone.